Internet Engineering Task Force (IETF) F. Gont
Request for Comments: 7112 Huawei Technologies
Updates: 2460 V. Manral
Category: Standards Track Ionos Networks
ISSN: 2070-1721 R. Bonica
Juniper Networks
January 2014
Implications of Oversized IPv6 Header Chains
Abstract
The IPv6 specification allows IPv6 Header Chains of an arbitrary
size. The specification also allows options that can, in turn,
extend each of the headers. In those scenarios in which the IPv6
Header Chain or options are unusually long and packets are
fragmented, or scenarios in which the fragment size is very small,
the First Fragment of a packet may fail to include the entire IPv6
Header Chain. This document discusses the interoperability and
security problems of such traffic, and updates RFC 2460 such that the
First Fragment of a packet is required to contain the entire IPv6
Header Chain.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7112.
Gont, et al. Standards Track [Page 1]RFC 7112 Implications of Oversized Header Chains January 2014Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................2
2. Requirements Language ...........................................3
3. Terminology .....................................................3
4. Motivation ......................................................4
5. Updates to RFC 2460 .............................................5
6. IANA Considerations .............................................5
7. Security Considerations .........................................6
8. Acknowledgements ................................................6
9. References ......................................................7
9.1. Normative References .......................................7
9.2. Informative References .....................................7
1. Introduction
With IPv6, optional internet-layer information is carried in one or
more IPv6 Extension Headers [RFC2460]. Extension Headers are placed
between the IPv6 header and the Upper-Layer Header in a packet. The
term "Header Chain" refers collectively to the IPv6 header, Extension
Headers, and Upper-Layer Header occurring in a packet. In those
scenarios in which the IPv6 Header Chain is unusually long and
packets are fragmented, or scenarios in which the fragment size is
very small, the Header Chain may span multiple fragments.
While IPv4 had a fixed maximum length for the set of all IPv4 options
present in a single IPv4 packet, IPv6 does not have any equivalent
maximum limit at present. This document updates the set of IPv6
specifications to create an overall limit on the size of the
combination of IPv6 options and IPv6 Extension Headers that is
allowed in a single IPv6 packet. Namely, it updates RFC 2460 such
that the First Fragment of a fragmented datagram is required to
contain the entire IPv6 Header Chain.
Gont, et al. Standards Track [Page 2]RFC 7112 Implications of Oversized Header Chains January 2014
It should be noted that this requirement does not preclude the use of